The present invention relates to the field of internal combustion engines, and more particularly to an improved internal combustion engine of the stratified charge type.
At present, many different designs and types of internal combustion engines are in use, the most common being the four-stroke gasoline engine. Of less significance are the two-stroke gasoline engine, rotary engines and both two and four-stroke diesel engines.
One of the factors influencing the efficiency of all types of engines is the degree to which complete burning of fuel injected into cylinders is obtained. In an effort to obtain more complete combustion so-called stratified charge type engines have been developed. The stratified charge engines which utilize a spark ignition are generally of two types. One type is the so called zone ignition in which the fuel-air mixture adjacent the spark plug is richer than that in other portions of the combustion chamber. Another type of stratified charge engine utilizing a spark ignition to initiate combustion has a precombustion chamber in which a richer fuel-air mixture is present than in the remainder of the combustion chamber. Some of this type of engine use a jet ignition in which a very small orifice provides communication between the precombustion chamber and the main combustion chamber. The disadvantage of such an engine is that the main combustion chamber cannot be charged with a fuel-air mixture through the precombustion chamber and the flame from the precombustion chamber which is used to ignite the leaner fuel-air mixture in the main combustion chamber is not well diffused.
Another type of stratified charge engine utilizing a precombustion chamber is one having a relatively large orifice which provides good communication between the precombustion chamber and the main combustion chamber, permitting the main combustion chamber to be charged with a leaner fuel-air mixture directly through the precombustion chamber. A disadvantage of this type of engine is that the flame propagated from the precombustion chamber does not have a high velocity, and accordingly generally is incapable of successfully producing combustion at as lean fuel-air mixtures as the jet type ignition.